Cocciolone, R.Brameld, K.OLeary, P.Haan, E.Muller, P.Shand, K.2009-09-082009-09-082008Australian and New Zealand Journal of Obstetrics and Gynaecology, 2008; 48(5):492-5000004-86661479-828Xhttp://hdl.handle.net/2440/50794Aims: This study compares different screening strategies for the detection of Down syndrome and considers practical implications of using multiple screening protocols. Methods: The performance characteristics of each screening strategy were assessed based on datasets of Down syndrome (n = 11) and unaffected pregnancies (n = 1006) tested in both first and second trimester, as well as data from first trimester (n = 18 901) and second trimester (n = 40 748) pregnancies. Results: For a detection rate of 91%, the false positive rates for integrated and serum integrated screening were 2.5% and 6.3%, respectively, compared with combined first trimester (4.6%) and second trimester (12.6%) screening. Contingent and sequential screening protocols achieved detection rates of 82 to 91% with false positive rates between 2.6 and 2.9%. Contingent protocols require retesting of 15 to 20% of cases in the second trimester. Sequential and integrated protocols require retesting of 98 to 100% of cases in the second trimester. The various screening strategies did not always detect the same Down syndrome pregnancies. Conclusions: Combining first and second trimester markers for Down syndrome screening better defines the at-risk population. However, integrated protocols complicate management of screening programs and may not be suitable as primary screening strategies. It may be a better use of resources to refine current first and second trimester programs through improved access and new markers. We therefore suggest thinking twice before embracing integrated population screening programs.en© 2009 The Royal Australian and New Zealand College of Obstetricians and Gynaecologists Copyright © 2009 John Wiley & Sons, Inc.Down syndromeintegrated contingentfirst trimester screeningJournal article002008330710.1111/j.1479-828X.2008.00911.x0002603061000102-s2.0-5434909616441527Haan, E. [0000-0002-7310-5124]